Many types of vision testers are known including those previously described by the present applicant in U.S. Pat. Nos. 6,350,032 and 4,740,072. These disclosures are incorporated by reference herein.
Technology related to healthcare devices and procedures is continuously improving. This constant improvement makes it possible to identify new populations that are underserved by existing technologies and to also assist these newly identified populations. Advances in technology lead to the improvement and modification of existing devices so that new and old healthcare issues can be addressed in more efficient and effective ways.
Vision testing is one healthcare area that benefits greatly from improved technology. Current vision testing devices present an optical path from a front lens to an image display. The image display generally comprising a plurality of rows and columns of varying sizes and/or shapes wherein each row or column presents various characters for the patient to identify. These characters are often found on a rotating disk or test slides mounted on a rotatable drum. The image displays typically require an illumination source as the test characters on the rotating disk, rotatable test slide, or the like are located in light blocking viewing assemblies.
In use, the patient views every row and column and the test administrator specifies the characters or objects that the patient should focus on. While it is often necessary to test small children for vision problems, it is very difficult for children to understand the concept of rows and columns. The party performing the vision test may not be able to adequately explain the procedure or may not be sure the child is properly reading the column or row the tester is indicating. Misdiagnoses and inefficiencies are generated by this confusion.
Even where particular rows or columns are highlighted, the patient must understand concepts such as “left to right” or “top to bottom.” This can be difficult to convey to children, mentally handicapped patients, patients that are not fluent in the tester's language, or in other similar circumstances. For instance, certain cultures read left to right while other cultures read from the right to the left, and it is possible for the tester and patient to have a different understanding of how to “read” a highlighted row. Known methods for blocking certain rows and/or columns of the image display include manually adding parts to a vision testing apparatus. Vision testers require more efficient and effective means to test patients.
Vision tests are performed by testing a patient's sight at various simulated distances where “far” or “distance vision” is considered to be approximately 20 feet between the patient and an object and where “near” or “reading vision” is considered to be about 14 inches. Near and far testing can be conducted on known vision testing machines. This has been achieved via a lens, or set of lenses, that simulate the distance to be tested. The near/far lenses can be moved to intersect the optical path provided by the viewing assembly. The vision testing assembly does not move when the tester moves from near to far vision testing and vice-versa. Some vision testing devices use two or more distinct optical paths. This leads to bulky and overly complicated vision testing machines.
It should be understood that the natural line of sight for a person who is reading tends to be at a downward angle as the reading material is below the person's straight-ahead line of sight. As such, bifocals, trifocals and progressive lenses have varying magnification regions along the vertical axis of the lens with magnifications for near distance reading or writing located in the lower portion of the lens. Vision testing devices with only one optical path do not account for patients who have these types of lenses, which is to say that patients look straight into a vision testing device when testing “near” vision. This unnatural line of sight can lead to inaccurate results. Patients with corrective lenses are also inconvenienced by the need to adjust their lenses or head position to account for the unnatural line of sight. Even with multiple optical paths, the arbitrary angle supplied by the vision testing apparatus may not be optimum for a given patient. Moreover, it may be difficult for a patient to find the ideal angle and/or to hold their head or eyewear at that angle. For instance, aged patients may be unable to steadily hold their eyewear at the angle necessary to test the near vision portion of their corrective lenses.
It is also important for vision testing devices to provide portability or a small storage footprint, which is one reason devices with multiple optical paths are not favored as they tend to require more space. Yet, many vision testing machines cannot be collapsed or otherwise condensed and they, therefore, require bulky, hard storage or transport cases. Preferably, a vision testing apparatus would include a storage or transport configuration and a range of raised configurations. The configurations should be effective for patients of various heights.
A vision testing apparatus in accordance with the present invention provides a system for accurately testing vision. The present invention solves long-standing needs by providing a means to highlight and/or isolate portions of a vision test image so that a vision test is more efficiently and effectively administered. The apparatus of the present invention provides a storage/transport configuration and a range of raised configurations, and the apparatus operates in any configuration to serve patients of varying heights. The vision testing apparatus of the present invention also provides a means to rotate the a patient's line of sight without adjusting the apparatus' configuration. The adjustable line of sight mechanism simulates natural line of sight differences for distance and near vision testing.